000
FXUS63 KDDC 190501
AFDDDC
Area Forecast Discussion
National Weather Service Dodge City KS
1101 PM CST Sun Feb 18 2018
...updated aviation...
.SYNOPSIS...
Issued at 544 PM CST Sun Feb 18 2018
A dry cold front will sag south tonight into Monday, and then
stall out over SW Kansas Monday afternoon. A very large
temperature difference is expected Monday afternoon, with northern
counties below freezing, and areas along the Oklahoma border in
the 70s. The cold air will win the battle, with much colder
temperatures Tuesday and Wednesday. Expect moderating temperatures
Thursday and Friday. Dry weather will continue.
&&
.UPDATE...
Issued at 822 PM CST Sun Feb 18 2018
Cold front making excellent progress through NE Colorado,
with temperatures crashing quickly behind it (Cheyenne fell from
53 to 26 in one hour). Given the front`s momentum on satellite
imagery and these observations, updated Monday`s temperatures by
dropping them significantly (especially north of US 50). 00z NAM
and latest HRRR runs show the frontal boundary clearing the KS/OK
border now by 9 am, and indications are the cold air will win out.
Strong cyclogenesis is still expected in SE Colorado Monday
afternoon, and the boundary will likely still stall and retreat
northward. Some wild temperature differences and temperature
swings are likely across the southern counties during the day
tomorrow. But north of US 50, it looks like the cold air will
reign supreme.
UPDATE Issued at 533 PM CST Sun Feb 18 2018
Added areas of smoke to the Barber county vicinity, as smoke plume
from fire in NW Oklahoma (Woods county) continues to spread NE.
&&
.SHORT TERM...(This evening through Monday)
Issued at 311 PM CST Sun Feb 18 2018
Temperatures are a real challenge in the short term with a sharp
baroclinic zone becoming established in western Kansas Monday and
uncertainty about how much if any the shallow cold air will mix
out during the day Monday.
A cold front extended from eastern South Dakota across central
Nebraska to eastern Wyoming early this afternoon with pressure
rises of two to three millibars in three hours behind the front in
South Dakota and northern Nebraska behind an upper leveltrough
that was moving from eastern North Dakota into Manitoba. A deep
surface cyclone was centered in southeast Wyoming and northeast
Colorado. A sharp pressure gradient across Kansas was producing
howling south to southwest winds with frequent gusts to near 50
mph. Relative humidities were below 15% only in west central
Kansas, but the dry air should spread farther east by late
afternoon.
An upper levelvorticity maximum evident on satellite imagery off
the southwest British Columbia coast will continue to dig into
the mean long wave trough position in the western United States,
and the upper levelflow over the central United States will back
tonight and Monday. A weak upper leveltrough that extended from
Wyoming to northeast New Mexico will continue moving northeast
tonight, and a weak surface cyclone will ripple along the low
level baroclinic zone. The cold front will progress southward into
northern Kansas this evening in the wake of the weak cyclone and
should reach southern Kansas by morning. Temperatures tonight will
be mild for this time of the year with lows in the 40s and lower
50s across southern Kansas in advance of the cold front.
Temperatures likely will fall into the upper 20s behind the front
in northern Kansas.
The models are reasonably consistent in slowing the front to a
stop north of the Oklahoma border as cyclogenesis occurs in
Colorado as an upper leveltrough ejects from the long wave
position into eastern Colorado by Tuesday morning. Model soundings
suggest that stratus will develop north of the front but may
erode northward Monday afternoon. It usually is hard to erode cold
air once it is in place, but there is good consensus among the
model solutions that at least some erosion will occur. The air
behind the front is not true arctic air, and there should be quite
a bit of sun for some distance on the cold side of the front.
There will be a very substantial temperature gradient Monday with
temperatures holding in the lower 30s around Interstate 70 and
rising into the 70s south of the front.
.LONG TERM...(Monday night through Sunday)
Issued at 311 PM CST Sun Feb 18 2018
A long wave trough will persist in the western United States with
a strong upper levelridge from the Gulf of Mexico across Florida
to the western Atlantic Ocean. Minor upper level troughs will
move around the mean long wave position and lift out across the
central part of the country. Although the potential for beneficial
precipitation on southwest Kansas through the end of February is
minimal, there will be several opportunities for light
precipitation.
The upper leveltrough that will extend from the Dakotas into
eastern Colorado Tuesday morning will lift out to the northeast
and should extend from James Bay to Minnesota by Wednesday
morning. There may be enough isentropic lifting over the front to
produce light precipitation in south central Kansas Monday night.
The phase of the precipitation is not certain, but most of it
should fall before surface temperatures drop below freezing. Cold
air will surge southward across the Plains Monday night and
Tuesday, and temperatures Tuesday will vary from the 20s in
northern Kansas to near 50 along the Oklahoma border.
Another minor upper leveltrough will approach Wednesday, and
isentropic lifting over the cold air mass may produce some light
precipitation in central and southern Kansas. Temperatures will be
below freezing at the surface, and a warm layer aloft will
support the possibility of freezing rain or sleet. Yet another
upper leveltrough will approach Thursday and will provide an
opportunity for light precipitation.
A stronger upper leveltrough should reach Kansas about Saturday.
Warm air advection will occur Friday as a surface cyclone
develops in southeast Colorado, and temperatures should be above
freezing by the time precipitation develops Friday night and
Saturday. However, details in timing of the minor upper level
troughs and the thermal structure of the low levels of the
atmosphere are uncertain.
It still appears likely that the deep upper level low will weaken
and retrograde to the Canadian Arctic in early March and that an
area of high pressure will spread from northern Europe into
eastern Canada. A meanupper leveltrough is likely to persist in
the western United States, so chances for precipitation will
continue into early March.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1100 PM CST Sun Feb 18 2018
Watch observations upstream across northwest Kansas and northeast
Colorado. Front with post frontal stratus is the main concern for the
TAFpd. As stratus heads south, MVFR to possibly IFR cigs are expected
for KGCK/KHYS/KDDC by early morning (psbl KLBL). A second concern associated
with the stratus is if cigs will improve to VFR or if the clouds will
linger. Confidence in the evolution of the stratus is low at this time.
Otherwise, winds will switch with the fropa /w N winds 10-20 kt in
its wake.
&&
.FIRE WEATHER...
Issued at 333 AM CST Sun Feb 18 2018
Strong south to southwest winds will continue this afternoon into
the evening. Very dry air in west central Kansas will spread
slightly farther to the east, but relative humidities will not
fall below 20 percent east of a line from Hays to Liberal. The Red
Flag warning will be continued given the extremely dry fuels and
high winds even though relative humidity criteria will not be met.
Warm temperatures and gusty southwest winds near the Oklahoma
border will support active fire behavior Monday, but relative
humidities will remain above thresholds for fire weather
headlines.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 29 40 27 36 / 0 0 10 0
GCK 28 38 20 31 / 0 0 10 0
EHA 46 74 28 40 / 0 0 10 0
LBL 49 68 32 43 / 0 0 10 0
HYS 28 35 18 26 / 0 10 20 0
P28 53 66 37 46 / 0 10 30 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Turner
SYNOPSIS...Turner
SHORT TERM...Ruthi
LONG TERM...Ruthi
AVIATION...Sugden
FIRE WEATHER...Ruthi